Conventional stylus-based or pen-based devices, such as personal digital assistants (PDAs), offer a graphical user interface (GUI). In the GUI, menu objects are typically visually presented on a touch screen as graphical icons. A user can open a directory, start an application, or open a certain document by pointing to “activatable” graphical (menu) objects.
With most conventional pen-based devices, a point-to-activate interaction is used. That is, touching the pen to a menu object displayed on the touch screen immediately causes some action related to the touched object (e.g., opening the document or starting the application). However, this type of “touch-and-go” operation can occasionally result in an unintended and unexpected activation, such as when the user accidentally touches a displayed menu object without having the intent to start some action. The accidental launching of an application, or the opening of a file, is an annoyance to the user, and reduces the usability of the device.
In the conventional mouse-based GUI, the menu object selection and activation operations are separated. For example, a single click selects (focuses) an object, and a double click activates the object. However, there are few pen-based device which adopt this type of two-step activation.
With some pen-based UI, such as Windows CE™ (Microsoft Corporation), an object can be selected, without being activated, when it is pointed to for longer than some predetermined amount of time. However, this type of selection operation does not avoid the problem of mispointing, such as by accidentally touching the screen at a location that corresponds to a menu object.
It is also known in the prior art that some systems (such as an electronic tablet user interface) offer a drag-and-drop technique for a pen-based device. The typical procedures of drag-and-drop manipulation are: 1) select (focus) an object, 2) drag the object to a desired application icon, and 3) drop the object over the icon. However, since it is normally required to release the pen tip between the first and second operations, mis-selection can occur at this point, and the user may lose multiple focuses when pointing to an object.